1. Field
This disclosure relates to a lithium secondary battery.
2. Description of the Related Technology
A conventional lithium secondary battery can include a separator of an electric insulating porous film interposed between a positive electrode and a negative electrode, wherein an electrolyte containing a lithium salt is impregnated in the pores of film.
In the view of energy density, a conventional positive active material, such as LiCoO2, can have difficulty in achieving high voltage. Therefore, development of substitute material has been ongoing. High voltage spinel manganese-based lithium oxide has drawn a lot of attention for its ability to achieve high voltage. However, high voltage spinel-based battery systems use a voltage range providing a potential in a region of around 5V, so the cell may be degraded when a conventional electrolyte and separator are used. For example, a conventional electrolyte and separator are used in a lithium secondary battery system using the potential region of 4.2V may cause rapid degradation of the cell. Further, the decomposition of electrolyte may be precipitated on the negative electrode (or positive electrode) when the positive electrode (or negative electrode) including transition elements is reacted with the electrolyte, or the separator may be oxidized and degraded, causing to deterioration to the rechargeable battery.